liveMedia/TCPStreamSink.cpp

/**********
This library is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by the
Free Software Foundation; either version 3 of the License, or (at your
option) any later version. (See <http://www.gnu.org/copyleft/lesser.html>.)

This library is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for
more details.

You should have received a copy of the GNU Lesser General Public License
along with this library; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA
**********/
// "liveMedia"
// Copyright (c) 1996-2020 Live Networks, Inc.  All rights reserved.
// A sink representing a TCP output stream
// Implementation

#include "TCPStreamSink.hh"
#include <GroupsockHelper.hh> // for "ignoreSigPipeOnSocket()"

TCPStreamSink* TCPStreamSink::createNew(UsageEnvironment& env, int socketNum) {
  return new TCPStreamSink(env, socketNum);
}

TCPStreamSink::TCPStreamSink(UsageEnvironment& env, int socketNum)
  : MediaSink(env),
    fUnwrittenBytesStart(0), fUnwrittenBytesEnd(0),
    fInputSourceIsOpen(False), fOutputSocketIsWritable(True),
    fOutputSocketNum(socketNum) {
  ignoreSigPipeOnSocket(socketNum);
}

TCPStreamSink::~TCPStreamSink() {
  // Turn off any pending background handling of our output socket:
  envir().taskScheduler().disableBackgroundHandling(fOutputSocketNum);
}

Boolean TCPStreamSink::continuePlaying() {
  fInputSourceIsOpen = fSource != NULL;
  processBuffer();

  return True;
}

#define TCP_STREAM_SINK_MIN_READ_SIZE 1000

void TCPStreamSink::processBuffer() {
  // First, try writing data to our output socket, if we can:
  if (fOutputSocketIsWritable && numUnwrittenBytes() > 0) {
    int numBytesWritten
      = send(fOutputSocketNum, (const char*)&fBuffer[fUnwrittenBytesStart], numUnwrittenBytes(), 0);
    if (numBytesWritten < (int)numUnwrittenBytes()) {
      // The output socket is no longer writable.  Set a handler to be called when it becomes writable again.
      fOutputSocketIsWritable = False;
      if (envir().getErrno() != EPIPE) { // on this error, the socket might still be writable, but no longer usable
	envir().taskScheduler().setBackgroundHandling(fOutputSocketNum, SOCKET_WRITABLE, socketWritableHandler, this);
      }
    }
    if (numBytesWritten > 0) {
      // We wrote at least some of our data.  Update our buffer pointers:
      fUnwrittenBytesStart += numBytesWritten;
      if (fUnwrittenBytesStart > fUnwrittenBytesEnd) fUnwrittenBytesStart = fUnwrittenBytesEnd; // sanity check
      if (fUnwrittenBytesStart == fUnwrittenBytesEnd && (!fInputSourceIsOpen || !fSource->isCurrentlyAwaitingData())) {
	fUnwrittenBytesStart = fUnwrittenBytesEnd = 0; // reset the buffer to empty
      }
    }
  }

  // Then, read from our input source, if we can (& we're not already reading from it):
  if (fInputSourceIsOpen && freeBufferSpace() >= TCP_STREAM_SINK_MIN_READ_SIZE && !fSource->isCurrentlyAwaitingData()) {
    fSource->getNextFrame(&fBuffer[fUnwrittenBytesEnd], freeBufferSpace(), afterGettingFrame, this, ourOnSourceClosure, this);
  } else if (!fInputSourceIsOpen && numUnwrittenBytes() == 0) {
    // We're now done:
    onSourceClosure();
  }
}

void TCPStreamSink::socketWritableHandler(void* clientData, int /*mask*/) {
  TCPStreamSink* sink = (TCPStreamSink*)clientData;
  sink->socketWritableHandler1();
}

void TCPStreamSink::socketWritableHandler1() {
  envir().taskScheduler().disableBackgroundHandling(fOutputSocketNum); // disable this handler until the next time it's needed

  fOutputSocketIsWritable = True;
  processBuffer();
}

void TCPStreamSink::afterGettingFrame(void* clientData, unsigned frameSize, unsigned numTruncatedBytes,
				struct timeval /*presentationTime*/, unsigned /*durationInMicroseconds*/) {
  TCPStreamSink* sink = (TCPStreamSink*)clientData;
  sink->afterGettingFrame(frameSize, numTruncatedBytes);
}

void TCPStreamSink::afterGettingFrame(unsigned frameSize, unsigned numTruncatedBytes) {
  if (numTruncatedBytes > 0) {
    envir() << "TCPStreamSink::afterGettingFrame(): The input frame data was too large for our buffer.  "
	    << numTruncatedBytes
	    << " bytes of trailing data was dropped!  Correct this by increasing the definition of \"TCP_STREAM_SINK_BUFFER_SIZE\" in \"include/TCPStreamSink.hh\".\n";
  }
  fUnwrittenBytesEnd += frameSize;
  processBuffer();
}

void TCPStreamSink::ourOnSourceClosure(void* clientData) {
  TCPStreamSink* sink = (TCPStreamSink*)clientData;
  sink->ourOnSourceClosure1();
}

void TCPStreamSink::ourOnSourceClosure1() {
  // The input source has closed:
  fInputSourceIsOpen = False;
  processBuffer();
}